Although it seems that there is no excellent tumor marker for lung cancer, we have developed a process for efficiently producing an antihuman pulmonary adenocarcimona monoclonal antibody by using human normal lung tolerant mice (cf. JP-A-60-190721 corresponding to EP-A-0156578) (the term "JP-A" used herein means an unexamined published Japanese patent application.) and thus established antihuman pulmonary adenocarcinoma monoclonal antibodies useful for serodiagnosis of pulmonary adenocarcinoma including SLC-1 (cf. JP-A-61-234357), ALC-1 (cf. JP-A-61-234358), ALC-186 (cf. JP-A-62-80558, JP-A-62-83898 corresponding to EP-A-0218257) and ALC-454 (cf. JP-A-63-19561 corresponding to EP-A-0252769). However, each of these monoclonal antibodies, which would recognize an antigen released in the serum of a patient suffering from lung cancer, is not always suitable for the cytological or histlogical diagnosis or treatment of this disease, though it is useful in the serodiagnosis thereof. Namely, a monoclonal antibody which recognized not a released antigen but rather a cancer cell membrane surface antigen is preferable for these purposes.